Effects of curves on graph perception

Curves have long been used for graph visualization with increased popularity in recent years. Curves are mainly used for two purposes: one is to increase readability and the other is to enhance visual aesthetic pleasingness. Although curves can be visually pleasing, the introduction of curves in graph drawing does not increase readability automatically. Attempts have been made to investigate the usability of curved drawings. However, the results on the effect of curves per se on human graph comprehension has not been conclusive. This paper presents a user study that is to examine the effect of curves when they are introduced to remove crossings. Twenty-six participants were recruited to perform typical graph reading tasks. Task performance and user preference data were collected for analysis. The results indicate that curves can be a useful alternative when crossings are to be present in straight-line drawings. The findings of the study are also discussed along with some of our future research activities in this paper.